Recently, mobile communication terminals such as mobile phones are proliferating, enabling individuals to exchange information with others with almost no restrictions on place. In addition, there is also the development of information processing technology that supports information sharing between acquaintances and connections between people, such as social networking services (SNS).
For example, Patent Literature 1 discloses technology that manages and updates a social graph by judging a degree of association between users, on the basis of a communication history of a mobile terminal. Also, Patent Literature 2 discloses technology that estimates a person having a high information propagation ability, on the basis of a communication history of a communication terminal.